The present disclosure relates to a construction machine. More particularly, the present disclosure relates to an engine idling control system for an excavator.
Idling refers to a state in which a vehicle or a machine is stopped while an engine is operating. Exhaust emitted in such a state by the vehicle or the machine pollutes the atmosphere since the amount of carbon monoxide and the amount of nitrogen oxide produced are higher than when the vehicle or the machine is operated in a state of acceleration, constant speed, deceleration, etc. Thus, it may become a factor in lowering fuel efficiency. Accordingly, techniques have been developed to lower the environmental pollution level, and reduce fuel consumption by lowering the engine RPM per minute during such an idling state.
Until now, in an engine idling system applied to an excavator, an idling engine RPM is set slightly high for engine starting according to a height of the bucket, and for a rapid response according to a load. As a result of investigating driver usage patterns by RPM, a low idling RPM comprises about 20%, and there are situations where the engine is maintained at the high idling RPM without operation, whereby fuel is consumed unnecessarily.
In an engine idling system applied to a conventional construction machine, an idling engine RPM is set relatively high to ensure a fast response when a load is applied. Accordingly, an engine RPM may be controlled to rapidly respond to a load required for a work while decreasing fuel consumption and also lowering an engine RPM in an idling state.
According to one aspect of the present disclosure, there is provided an engine idling control system capable of setting the lowest idling engine RPM required for maintaining a vehicle operation as the lowest idling RPM, and controlling the engine RPM to recover to a conventional idling RPM required for rapidly responding when a work mode is activated by a lock lever switch that activates the work mode. In addition, when a machine is not used for a certain time period, the engine idling control system sets the machine to enter an auto idle mode, and controls the machine to operate in the lowest idling RPM according to a condition.
When a load required for a work is applied to an engine while the machine is a state of the lowest idling RPM, the time for the engine to reach the required RPM may delay the work. In other words, a response for the same may be delayed. Accordingly, in order to compensate such a delay, an E-ECU (an engine controlling electronic control unit (ECU)) receives in advance a signal that represents a torque value calculated by a V-ECU (a vehicle controlling electronic control unit (ECU)), and controls the engine to prepare an RPM required for the work. Thus, an engine RPM drop caused by the delayed response, or a response time is reduced so that work performance of the machine may not be affected.
An engine idling control system according to the present disclosure may decrease fuel consumption in an idling state by lowering an engine RPM maintained when a construction machine is not working, and by lowering an RPM in an auto idle mode more than a conventional RPM technique. In addition, an engine response in a low RPM may be compensated by maintaining the engine RPM in a low state in an idling state and by introducing an engine transient mode. Thus, an engine RPM drop or a response time may be reduced.